Initial commit

libsst-os/SST_Mmap_Win32.c

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+/*
+	SST_Mmap_Win32.c
+	Author: Patrick Baggett <ptbaggett@762studios.com>
+	Created: 12/23/2011
+
+	Purpose: 
+
+	libsst-os memory mapped file I/O functions for Win32 systems (Windows 7 or later)
+
+	License:
+
+	This program is free software. It comes without any warranty, to
+	the extent permitted by applicable law. You can redistribute it
+	and/or modify it under the terms of the Do What The Fuck You Want
+	To Public License, Version 2, as published by Sam Hocevar. See
+	http://sam.zoy.org/wtfpl/COPYING for more details.
+
+*/
+
+#include "Win32Private.h"
+#include <SST/SST_Mmap.h>
+#include <SST/SST_SysMem.h> /* SST_PROTECT_XXXXX constants */
+#include <SST/SST_Assert.h>
+
+#if !defined(FILE_MAP_EXECUTE) /* Added in Windows XP SP2 */
+	#define FILE_MAP_EXECUTE 0x20
+#endif
+
+static uint32_t allocGranularity;
+
+void __libsst_init_mmapsize()
+{
+	SYSTEM_INFO si;
+
+	GetNativeSystemInfo(&si);
+
+	allocGranularity = (uint32_t)si.dwAllocationGranularity;
+}
+
+
+/*************************************************************************/
+
+uint32_t SST_OS_GetMmapGranularity(void)
+{
+	return allocGranularity;
+}
+
+/*************************************************************************/
+
+SST_MemoryMap SST_OS_CreateMmap(SST_File file, uint64_t offset, size_t mapLength, int mode)
+{
+	SST_File_Win32* fp = (SST_File_Win32*)file;
+	SST_MemoryMap_Win32* mm;
+	DWORD access, offsetLow, offsetHigh;
+	void* ptr;
+
+	SST_OS_DebugAssert(file != NULL, "File handle may not be NULL");
+	SST_OS_DebugAssert((mode & (~(SST_PROTECT_READ|SST_PROTECT_WRITE|SST_PROTECT_EXEC))) == 0, "The mode bits may only contain SST_PROTECT_READ/WRITE/EXEC and nothing else");
+	SST_OS_DebugAssert((offset & (SST_OS_GetMmapGranularity()-1)) == 0, "Offset must be aligned to system granularity. Use SST_OS_GetMmapGranuality() to determine this");
+	SST_OS_DebugAssert((offset == 0 && mapLength == 0) || mapLength > 0, "Map length must be non-zero OR offset and length must both be zero (map whole file)");
+
+	/* No file mapping yet? */
+	if(fp->hMap == NULL)
+	{
+		DWORD pageProt;
+
+		/* Decide on protection flags. See SST_File_Win32.c/SST_OS_OpenFile() for the 'case' values */
+		switch(fp->accessFlags)
+		{
+			case GENERIC_READ | GENERIC_EXECUTE: pageProt = PAGE_EXECUTE_READ; break;
+			case GENERIC_READ | GENERIC_WRITE | GENERIC_EXECUTE: pageProt = PAGE_EXECUTE_READWRITE; break;
+			default: return NULL;
+		}
+
+		/* Actually create the file mapping */
+		fp->hMap = CreateFileMappingA(fp->hFile, NULL, pageProt, 0, 0, NULL);
+		if(fp->hMap == NULL)
+			return NULL;
+	}
+	/* Windows is weird about its flags: it allows {R, W} + {X}, so only 4 combinations of
+	possible values. However, the 'W' bit implies 'R'. */
+	if(mode & SST_PROTECT_READ)
+		access = FILE_MAP_READ;
+	if(mode & SST_PROTECT_WRITE) 
+		access = FILE_MAP_WRITE; /* This is actually r/w, which is why we don't use "else if(...)" */
+	if(mode & SST_PROTECT_EXEC)
+		access |= FILE_MAP_EXECUTE; 
+	
+	offsetLow = (DWORD)(offset & 0xFFFFFFFF);
+	offsetHigh = (DWORD)(offset >> 32);
+
+	/* Windows already treats a mapLength == 0 as "map to end of file". We just ensure (at the top) that
+	offset == 0 so it really means "map from beginning to end". */
+
+	ptr = MapViewOfFileEx(fp->hMap, access, offsetHigh, offsetLow, mapLength, NULL);
+
+	if(ptr == NULL)
+		return NULL;
+
+	/* Allocate a memory map region */
+	mm = (SST_MemoryMap_Win32*)HeapAlloc(GetProcessHeap(), 0, sizeof(SST_MemoryMap_Win32));
+	if(mm == NULL)
+	{
+		UnmapViewOfFile(ptr);
+		return NULL;
+	}
+
+	if(mapLength == 0)
+	{
+		LARGE_INTEGER size;
+		GetFileSizeEx(fp->hFile, &size);
+
+		mapLength = (size_t)size.QuadPart;
+	}
+
+	mm->offset = offset;
+	mm->len = mapLength;
+	mm->base = ptr;
+	#ifdef _DEBUG
+	mm->owner = fp;
+	fp->nrMmaps++;
+	#endif
+
+	return (SST_MemoryMap)mm;
+}
+
+/*************************************************************************/
+
+void SST_OS_DestroyMmap(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_Win32* mm = (SST_MemoryMap_Win32*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	UnmapViewOfFile(mm->base);
+
+	#ifdef _DEBUG
+	mm->base = NULL;
+	mm->owner->nrMmaps--;
+	#endif
+
+	HeapFree(GetProcessHeap(), 0, mm);
+}
+
+/*************************************************************************/
+
+void* SST_OS_GetMmapBase(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_Win32* mm = (SST_MemoryMap_Win32*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	return mm->base;
+}
+
+/*************************************************************************/
+
+size_t SST_OS_GetMmapSize(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_Win32* mm = (SST_MemoryMap_Win32*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	return mm->len;
+}
+
+/*************************************************************************/
+
+uint64_t SST_OS_GetMmapOffset(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_Win32* mm = (SST_MemoryMap_Win32*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	return mm->offset;
+}
+
+/*************************************************************************/
+
+void SST_OS_SyncMmap(SST_MemoryMap mappedRegion)
+{
+	SST_MemoryMap_Win32* mm = (SST_MemoryMap_Win32*)mappedRegion;
+
+	SST_OS_DebugAssert(mappedRegion != NULL, "Memory map handle may not be NULL");
+
+	FlushViewOfFile(mm->base, mm->len);
+}
+